In the electronics industry there is a steady trend towards manufacturing microprocessors and memory devices of increasingly high speed and large information storage capacity. This requires the individual electrical devices such as transistors, etc. within the microprocessors to be fabricated at an increasingly small scale. The metallic electrical interconnects between the devices also need to be miniaturized. As device and interconnect dimensions fall below one-quarter of a micron, the choice of interconnect metal becomes critical.
Chemical vapor deposition of copper metal using fluorinated organometallic copper compounds has been widely used in the electronics industry for the above applications. Specifically, copper metal is deposited on metallic substrates or other electrically conducting portions of a substrate employing CVD methods. The ability of the organo copper complexes to deposit a metallic copper film which has good adhesion to the substrate and produce a copper film having low resistivity are two requirements of the organo copper complexes and the CVD process employed.
One class of organo copper complexes widely used for the deposition of copper films by a CVD process is a copper(+1)(β-diketonate)(L) complex where (L) represents a stabilizing ligand, typically a non-aromatic unsaturated group including silylolefins and silylalkynes. The following patents are representative of copper(+1)(β-diketonate)(L) complex for chemical vapor deposition in the electronics industry.
U.S. Pat. No. 5,085,731 discloses organometallic complexes based upon copper(+1)(β-diketonate)(L) complexes where (L) is a silylolefin stabilizing ligand. These are represented by the formula: wherein R1 and R3 are each independently C1-C8 perfluoroalkyl, R2 is H, F or C1-C8 perfluoroalkyl, R4 is H, C1-C8 alkyl, or Si(RN)3, each R5 is independently H or C1-C8 alkyl, and each R6 is independently phenyl or C1-C8 alkyl. One type of complex is prepared by reacting a copper salt, e.g., copper chloride with the potassium salt of hexafluoroacetylacetone, i.e., (K+1(hfac)−1), and a silylolefin in hexane or other solvent.
U.S. Pat. No. 5,187,300 discloses organometallic copper complexes suited for selectively depositing copper films onto electrically conducting portions of a substrate under CVD conditions. These copper complexes are based upon copper(+1)(β-diketonate)(L) where (L) is a silylalkyne stabilizing ligand. This type of complex is prepared by the reaction of the potassium salt of hexafluoroacetylacetone with copper chloride in the presence of a silylalkyne stabilizing ligand. These complexes have the formula:                 wherein R1 and R3 are each independently C1-C8 perfluoroalkyl, R2 is H, F or C1-C8 perfluoroalkyl, R4 is H, C1-C8 alkyl, phenyl, or Si(R5)3, and each R5 is independently CL-C8 alkyl or phenyl.        
U.S. Pat. No. 5,098,516 discloses organo copper compounds of the formula: wherein R1 and R3 are each independently C1-C8 perfluoroalkyl, R2 is H or C1-C8 perfluoroalkyl and L is carbon monoxide, an isonitrile or an unsaturated hydrocarbon ligand containing at least one non-aromatic unsaturation. These copper(+1)(β-diketonate)(L) compounds are also prepared by the reaction of the potassium salt of hexafluoroacetylacetone with copper chloride in the presence of a stabilizing ligand.
U.S. Pat. No. 6,096,913 discloses the synthesis of copper(+1)(β-diketonate)(L) type complexes by the reaction of a β-diketone with cuprous oxide in the presence of stabilizing ligand (L) and finely divided copper powder to suppress the formation of unwanted copper(+2)bis(hexalluoroacetylacetonate). The process is described by the following equation:2Hhfac+Cu2O+2(L)=2Cu(+1)(hfac)(L)+H2O 